Re: Calling toString on function proxy throws TypeError exception

2015-10-27 12:47 GMT-04:00 Jordan Harband : > > Shouldn't tests in existing code that rely on `Function#toString` not > throwing to indicate that something is callable, or throwing to indicate > that it is not, remain true for a function proxy? > Excluding some host objects (as

Re: Calling toString on function proxy throws TypeError exception

> Le 26 oct. 2015 à 20:20, Allen Wirfs-Brock a écrit : > > >> On Oct 26, 2015, at 11:20 AM, Mark Miller wrote: >> >> I like the idea a function proxy is more encapsulating of its implementation >> than a function is. >> >> I also like the idea of

Re: Calling toString on function proxy throws TypeError exception

> Le 27 oct. 2015 à 09:35, Claude Pache a écrit : > > >> Le 26 oct. 2015 à 20:20, Allen Wirfs-Brock a écrit : >> >> >>> On Oct 26, 2015, at 11:20 AM, Mark Miller wrote: >>> >>> I like the idea a function proxy is more

Re: Calling toString on function proxy throws TypeError exception

On 10/27/15 4:35 AM, Claude Pache wrote: it is that, for any callable object, it will return a string and not throw, because it was so since the dawn of JS. It's totally false for random "host objects" with a [[Call]] in ES5, per spec and in at least some implementations. As you can tell in

Re: Calling toString on function proxy throws TypeError exception

On 10/27/15 9:14 AM, Boris Zbarsky wrote: On 10/27/15 4:35 AM, Claude Pache wrote: it is that, for any callable object, it will return a string and not throw, because it was so since the dawn of JS. It's totally false for random "host objects" with a [[Call]] in ES5, per spec and in at least

Re: Calling toString on function proxy throws TypeError exception

Notice that whatever we decide on the issue, functionProxy.toString() will work regardless, since you'd be getting the toString method itself through the membrane. functionProxy.toString will be a function proxy for the target.toString method. The invocation on the toString proxy with

Re: Calling toString on function proxy throws TypeError exception

Mark: considering that explicitly invoking a builtin prototype method, expecting a throw, to test for the [[Call]] internal slot, was the branding approach the committee agreed to preserve when it reaffirmed Symbol.toStringTag, as an alternative to `Object#toString.call`, I think Claude's point

Re: Calling toString on function proxy throws TypeError exception

> Le 27 oct. 2015 à 15:52, Mark S. Miller a écrit : > > Notice that whatever we decide on the issue, functionProxy.toString() will > work regardless, since you'd be getting the toString method itself through > the membrane. functionProxy.toString will be a function proxy

Re: Calling toString on function proxy throws TypeError exception

Non-membraned proxies are irreparably non-transparent. This case is not worth worrying about. On Tue, Oct 27, 2015 at 1:05 PM, Claude Pache wrote: > > > Le 27 oct. 2015 à 15:52, Mark S. Miller a écrit : > > > > Notice that whatever we decide on the

Re: Calling toString on function proxy throws TypeError exception

> On Oct 27, 2015, at 2:37 AM, Claude Pache wrote: > > > Naturally, I meant: > > ```js > Function.isGenerator = function (f) { > return typeof f == "function" && f.toString().match(/^function\s*\*/) != > null > } > ``` > > —Claude > >> >> That function will work

Re: Calling toString on function proxy throws TypeError exception

On 10/27/15 12:47 PM, Jordan Harband wrote: I think Claude's point ("The expectation is not that `F.p.toString` will always return something useful; it is that, for any callable object, it will return a string and not throw, because it was so since the dawn of JS.") is the one that convinces me.

Re: Calling toString on function proxy throws TypeError exception

> Le 27 oct. 2015 à 18:41, Allen Wirfs-Brock a écrit : > > > That said, I think it is plausible that the predicate in step 2 of > http://tc39.github.io/ecma262/#sec-function.prototype.tostring > could be

Re: Calling toString on function proxy throws TypeError exception

> Le 27 oct. 2015 à 14:14, Boris Zbarsky a écrit : > > On 10/27/15 4:35 AM, Claude Pache wrote: >> it is that, for any callable object, it will return a string and not throw, >> because it was so since the dawn of JS. > > It's totally false for random "host objects" with a

Re: Calling toString on function proxy throws TypeError exception

> On Oct 26, 2015, at 11:20 AM, Mark Miller wrote: > > I like the idea a function proxy is more encapsulating of its implementation > than a function is. > > I also like the idea of treating a function proxy as a builtin callable, > rather than a function written in JS,

Re: Calling toString on function proxy throws TypeError exception

Only because typeof f === 'function' divides the world into callables and non callables. On Oct 26, 2015 3:20 PM, "Allen Wirfs-Brock" wrote: > > > > On Oct 26, 2015, at 11:20 AM, Mark Miller wrote: > > > > I like the idea a function proxy is more

Re: Calling toString on function proxy throws TypeError exception

> On Oct 23, 2015, at 6:43 AM, Claude Pache wrote: > > Almost every method found on `Function.prototype` "works" (or, at least, does > not throw a TypeError before trying to work) if and only if the target is > callable, or if and only if `typeof` applied to the target

Re: Calling toString on function proxy throws TypeError exception

I like the idea a function proxy is more encapsulating of its implementation than a function is. I also like the idea of treating a function proxy as a builtin callable, rather than a function written in JS, and return something like "function () { [function proxy] }" as Tom suggested or

Re: Calling toString on function proxy throws TypeError exception

Almost every method found on `Function.prototype` "works" (or, at least, does not throw a TypeError before trying to work) if and only if the target is callable, or if and only if `typeof` applied to the target produces `"function"`. That should not be different for

Re: Calling toString on function proxy throws TypeError exception

2015-10-22 23:09 GMT+02:00 Allen Wirfs-Brock : > > > Why would it be reasonable to do this for `toString`, but not also `call`, > `apply`, and `bind`? And ultimately this problem exists for all built-in > methods that have have internal state dependencies. I just don’t see

Re: Calling toString on function proxy throws TypeError exception

I know that's true in general. But we made a few exceptions, especially for functions and arrays. I thought F.p.toString was one, but maybe not. I just don't remember. On Thu, Oct 22, 2015 at 2:36 PM, Allen Wirfs-Brock wrote: > > On Oct 22, 2015, at 11:23 AM, Mark S.

Re: Calling toString on function proxy throws TypeError exception

> On Oct 22, 2015, at 11:43 AM, Mark S. Miller wrote: > > I know that's true in general. But we made a few exceptions, especially for > functions and arrays. I thought F.p.toString was one, but maybe not. I just > don't remember. There are no such special cases that I’m

RE: Calling toString on function proxy throws TypeError exception

-discuss <es-discuss@mozilla.org> Subject: Calling toString on function proxy throws TypeError exception According to https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function/toString<https://na01.safelinks.protection.outlook.com/?url=ht

Re: Calling toString on function proxy throws TypeError exception

> On Oct 22, 2015, at 11:23 AM, Mark S. Miller wrote: > > Tom, this doesn't sound right to me. Didn't we intend > Function.prototype.toString to be transparent thru function proxies? > > cc'ing Allen and Brian > There is nothing unique to `toString` going on there. This

Re: Calling toString on function proxy throws TypeError exception

Ok, that all makes sense and is fine with me. Thanks for clarifying. Tom, I'm still curious what you remember? On Thu, Oct 22, 2015 at 2:59 PM, Allen Wirfs-Brock wrote: > > On Oct 22, 2015, at 11:43 AM, Mark S. Miller wrote: > > I know that's true

Calling toString on function proxy throws TypeError exception

According to https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function/toString `Function.prototype.toString` is supposed to throw a `TypeError` exception when used on a function proxy. That's also consistent with how it's defined at

Re: Calling toString on function proxy throws TypeError exception

2015-10-22 21:03 GMT+02:00 Mark Miller : > Ok, that all makes sense and is fine with me. Thanks for clarifying. > > Tom, I'm still curious what you remember? > What I remember is that the original direct proxies spec did the transparent forwarding. wiki.ecmascript.org still

Re: Calling toString on function proxy throws TypeError exception

> On Oct 22, 2015, at 1:38 PM, Tom Van Cutsem wrote: > > ... > I cannot recall any specific discussions on why that behavior was changed to > throwing a TypeError instead. The only reason I can come up with is that it > could be deemed a violation of the proxy's